firewatcher

Watch a log stream (journald, syslog, or any file) for incident patterns, then persist a window of surrounding messages to a durable location — including a network filesystem — so the record survives even if the machine later dies.

The watcher prefers journalctl --follow when journalctl is on PATH. On hosts without journald it falls back to /var/log/syslog, then /var/log/messages, or --log-file. Running the daemon does not require systemd; only --install-service / --uninstall-service do.

Install

pip install firewatcher

From a clone of this repository:

pip install .

Requires Python 3.6+. No third-party runtime dependencies.

Quick start

firewatcher /etc/firewatcher/patterns.d
firewatcher -t 300 -o /var/log/captured_messages/ /etc/firewatcher/patterns.d

A directory argument loads every non-hidden pattern file inside it. Files ending in .regex are compiled as regular expressions. Any other pattern file is treated as fnmatch (bash-like) substrings, with * added on both ends.

--install-service seeds /etc/firewatcher/patterns.d with example patterns when that directory is empty. The examples/ directory in the source tree is not installed onto PATH by pip install; copy those files from a clone, or let --install-service write them.

On a match, firewatcher writes:

• a per-incident capture under {output-folder}/{YYYY-MM}/…
• a line in {output-folder}/journal.log

Live capture is written as lines arrive, so a copy can already be on another filesystem if the host then disappears.

systemd service

sudo firewatcher --install-service
sudo firewatcher --print-unit
sudo firewatcher --uninstall-service

--install-service writes /etc/systemd/system/firewatcher.service, creates the output directory, seeds /etc/firewatcher/patterns.d/ with example patterns only if that directory is empty, then systemctl daemon-reload && systemctl enable --now firewatcher.

If systemd is not available, --install-service and --uninstall-service print a warning and exit. --print-unit still works so you can copy the unit elsewhere.

Useful flags:

sudo firewatcher --install-service -o /mnt/logs/captured_messages \
  --requires-mounts-for /mnt/logs/captured_messages \
  /etc/firewatcher/patterns.d

Options

Author

Yufei Pan (pan@zopyr.us)

License

GPL-3.0-or-later